1. Field of the Invention
The invention relates generally to a differential mechanism, which transmits rotating power to the wheels of a motor vehicle.
2. Description of the Prior Art
An engaged electronic locking differential (ELD) mechanically couples a side gear to the differential case when actuated by an electromagnetic coil connected to a voltage source, which is controlled in some cases by a control module.
The driven wheels are the wheels that are coupled by the electronic locking differential. When activated the electronic locking differential prevents relative motion between the driven wheels and transmits engine combustion torque multiplied by the transmission and axle ratio to the wheels. With the electronic locking differential engaged, in most instances, the maximum axle input torque (AIT) is limited by the skid torque of the wheels on the surface having the highest coefficient of friction surface, the largest tire surface area and the highest gross weight vehicle.
When slip between the driven wheels occurs due to traction loss on a slippery surface, engagement of the electronic locking differential generates the maximum available traction force, whereas an open differential will generate a total traction force that is twice the force on the wheel having the lower coefficient of friction.
ELD functionality includes making changes between on/off states, engage/disengage states, or intermittent states that transfer a greater percentage of available torque to the driven wheel having the higher coefficient of friction, similar to a limited slip differential bias ratio.
On/off functionality of the ELD may be controlled manually, such as by changing the state of an actuator switch that is linked by a wiring harness to a control module.
A need exists in the motor vehicle industry for a control strategy that enables active or automatic control of the electronic locking differential functionality, thereby eliminating need for any manual actuation and electrical wiring that otherwise would be required to connect the actuator input and a controller.